This invention relates generally to threshing and more particularly to threshing machines having crop material conveyors.
While the terms "grain", "straw", and "tailings" are used principally throughout this specification for convenience, it should be understood that these terms are not intended to be limiting. Thus "grain" refers to that part of the crop material which is threshed and separated from the discardable part of the crop material which is referred to as "straw". Incompletely threshed ears are referred to as "tailings". Also, the terms "forward", "rearward", "left", "right" etc. when cited in connection with the combine harvester and/or components thereof are determined with reference to the forward operative travel of the combine harvester in the field and should not be understood to be limiting.
In known combine harvesters, grain is threshed and separated in a threshing and separating mechanism and the separated grain, together with impurities of all sorts, such as chaff, dust, straw particles, tailings, is fed to a clearing mechanism for cleaning. Clean grain is collected and fed to a graintank for temporary storage. The tailings are separated from the clean grain and impurities for reprocessing. This reprocessing either means recycling the tailings through the threshing and separating mechanism or treating them in a separate tailings rethreshing means. In both cases the tailings are conveyed through an elevator which usually is of the paddle type.
The present invention is concerned with this tailings return elevator and while the invention conceivably can be applied either on so-called conventional combine harvesters with separating means comprising straw walkers, or on so-called rotary combine harvesters with axial flow type threshing and separating rotors, the invention is particularly useful on rotary combines of the type comprising one or more transversely extending threshing and/or separating rotors of which at least one end extends beyond the side edge of the cleaning mechanism disposed therebelow.
In conventional combine harvesters, wherein the tailings are recycled through the threshing and separating mechanisms a tailings elevator, which usually is of the paddle type, extends at one side of the machine between a location beneath the cleaning mechanism where tailings are collected and a location forwardly and generally above the level of the threshing means at one side thereof and at which location the elevator supplies tailings to a transverse tailings distributing auger. This arrangement of the tailings elevator and distributing auger is quite long and hence expensive and moreover it takes up much room whereby it is quite cumbersome and also whereby access to other components of the machine and drive means therefore is hampered considerably.
Furthermore, in rotary combine harvesters of the type comprising one or more transversely extending threshing and/or separating rotor assemblies of which at least one end extends beyond the side edges of the cleaning mechanism which is disposed therebelow, additional conveyor means are required for conveying crop material which is separated at said end toward the cleaning device. This again takes up quite some room and increases the cost. Also the material separated in these separator portions is not at all evenly spread over the full width of the cleaning mechanism, whereby uneven loading or overloading of the latter may occur.
Also, during recent years, the size and more especially the capacity of combines have increased considerably which means that the threshing, separating and cleaning means have to be capable of handling considerably increased volumes of crop material. With the present large capacity machines, even small percentages of tailings represent a considerable volume. Hence the tailings return elevator and tailings distributor auger must be quite sizeable and also recycling of these volumes of tailings through the threshing, separating and cleaning means often leads to an uneven loading and/or an overloading of the various components both of which are disadvantages as both ultimately result in considerable losses.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations as set forth above.